Continuous renal replacement therapy (CRRT), also known as continuous blood purification (CBP), is a new blood purification method. In 1995, the first International Conference on Continuous Renal Replacement Treatment recommended the use of a continuous 24-hour or near 24-hour continuous blood purification therapy to replace the purification method for the damaged kidney function, that is, continuous renal replacement therapy. Continuous renal replacement therapy includes continuous arteriovenous, continuous veno-venous hemofiltration (CAVH, CVVH), continuous arteriovenous, veno-venous hemodialysis (CAVDH, CVVDH), and continuous arteriovenous, veno-venous hemodiafiltration (CAVHDF, CVVHDF).
Hemodialysis refers to drawing the blood out of the body to remove metabolic wastes and impurities in the blood through the osmotic membrane of the hemodialysis machine, and then transporting the purified blood back into the body, which is commonly known as “kidney cleansing” and “blood cleansing”. Hemodialysis can be used for renal failure patients, or those with blood poisoning but other bodies cannot discharge the toxic substances themselves. The blood in the body is drained to the outside, and through a dialyzer composed of numerous hollow fibers, the blood and electrolyte solution similar to the organic concentration (dialyzate) have material exchange via dispersion/convection inside and outside hollow fibers, to remove the metabolic wastes in the body and maintain electrolyte and acid-base balance; and remove excess water in the body.
If the continuous renal replacement therapy or hemodialysis treatment therapy is needed by the patients in the event of active bleeding, recent major surgery, severe trauma, coagulation dysfunction and other high-risk bleeding conditions, anticoagulation is to ensure that this treatment is one of the basic conditions for the smooth progress of this treatment when performing this blood purification treatment. At present, regional citrate anticoagulation (RCA), i.e., RCA-CRRT and RCA-HD, is mostly used. The principle is as follows: continuous input of sodium citrate solution is made when the human blood is led out, in which case the calcium ion in the sodium citrate chelate blood generates soluble complex calcium citrate that is difficult to dissociate, to reduce the calcium ion in the blood, prevent prothrombin conversion into the thrombin, so as to achieve the role of anticoagulation; when the extracorporeal blood enters into the body, the calcium ion solution is re-entered to reach the normal level of the human body and restore the body coagulation mechanism.
But at the current stage, the use of RCA method is still with more manual operation: manual calculation of the initial dosage—manual administration—manual blood drawing—manual test of electrolyte and other indicators (delay the time for adjusting dosage of administration)—manual calculation of the dosage—manual adjustment of the dosage metering. The manual process must be repeated once every 1-4 hours. In the time interval of one RCA treatment that lasts for several hours to dozens of hours, the above manual process must be repeated several times, which is cumbersome and time-consuming. Recently, some blood purification devices reduce the manual operation steps and can automatically input the citrate salt anticoagulant, but the input volume and speed still need to be manually adjusted and controlled, and it is necessary for separate blood collection and analysis. Moreover, the current clinical use cost of RCA therapy is high, with cumbersome operation, which restricts the clinical promotion of RCA. Currently, only about 10% of the patients or the wounded needing this therapy has the opportunity to receive this treatment.